Breast cancers with special genetic-phenotypic correlations

Abstract

Some invasive breast carcinomas are unique in that they show a specific recurrent genetic abnormality that is associated with distinct morphologic features. These tumors are triple-negative and are generally associated with a favorable prognosis compared with other triple-negative breast carcinomas. Adenoid cystic carcinoma is a biphasic epithelial-myoepithelial invasive carcinoma that like its salivary gland counterpart, is characterized by a recurrent t(6; 9) (q22-23; p23-24) translocation which results in the formation of a MYB-NFIB fusion gene. Secretory carcinoma shows a recurrent (12; 15); (p13; q25) translocation that results in an ETV6-NTRK3 gene fusion, which is also seen in mammary analogue secretory carcinoma of the salivary gland. Tall cell carcinoma with reversed polarity, previously called “breast tumor resembling the tall cell variant of papillary thyroid carcinoma,” and “solid papillary carcinoma with reverse polarity” shows IDH2 hotspot mutations, which are rare in other breast carcinomas. This review will provide an overview of the morphologic, immunohistochemical, molecular, and clinical features of these rare examples of breast cancers with special genetic–phenotypic correlations.